The present invention relates to a plasma-enhanced chemical vapor deposition process, especially the plasma-enhanced chemical vapor deposition process used to treat a web rolled through an evacuated chamber.
An example of such a process is described in Felts et al. U.S. Pat. No. 5,224,441, which is incorporated herein by reference. In this patent, gases, including a monomer (i.e., organosilicon), oxygen, and inert gas (i.e., helium), are introduced into the evacuated chamber. A glow discharge plasma is formed between two electrodes powered by an alternating current (AC) power supply. A web substrate flows over a drum electrode and is treated by the plasma so that a silicon oxide layer forms onto the web.
It is desired to run a plasma-enhanced chemical vapor deposition process at high currents to allow the substrate to be treated at high speeds, thus increasing productivity. The use of high currents can cause wrinkling or other damage to the web substrate.
It is desired to avoid these problems in the plasma enhanced chemical vapor deposition process.